The purpose of the carding operation is to turn raw material consisting of tufts of fibres, which have already undergone certain initial cleaning and opening processes, into a belt of untwisted fibres in the form of a web that is, as far as possible, free of impurities and non-homogeneities such as residual dirt from the previous processes, waste and tangles or “neps”.
As is known, in general terms, a carding machine comprises a main carding drum supplied by opening cylinders, generally termed “briseur”, while around it are a plurality of systems (a system of flats and auxiliary cleaning mechanisms and the like) which interact with the main drum in order to open, clean and attenuate the fibres.
To improve the efficiency of the interaction between the systems surrounding it and the main drum and obtain a fibre belt that has ever less twist and is of increasingly high impurity, and hence of better quality, modern types of carding machines use a multiple feed to the main drum.
One example of the above is disclosed, for example, in European Patent No. 927 779 in the name of the present Applicant.
The multiple feed to the main drum provides ideal conditions for the systems interacting with the main drum to operate effectively on the fibres.
However, it has also been observed that the opportunity to make the best use of the thin layer of fibres presented to the main drum by the multiple-feed system, and so obtain a fibre belt with a high degree of parallelization and cleanliness, is inherently limited by problems with the reliability of the systems themselves.
In other words, even though the systems interacting with the main drum are presented with a thin layer of fibre with good processing properties, nonetheless to achieve a high degree of parallelization and cleanliness of the fibre would still require the use of systems so advanced in their engineering properties as to make frequent maintenance necessary.
There is therefore a need to provide carding machines capable of improving the quality of the belt of fibres put out, while maintaining excellent characteristics of reliability and requiring little maintenance.